1. Field of the Invention
The present invention relates to a keyboard switch, and more particularly to a keyboard switch for supporting a key top with a plurality of link members.
2. Description of the Related Art
A conventional keyboard switch will now be explained with reference to FIG. 15. The conventional keyboard switch 21 includes a base frame 22 on the lower side, and a key top 23 on the upper side facing the base frame 22.
A membrane switch 24 formed by stacking three layers of film sheets is installed on the lower side of the base frame 22 and is inserted between a metal panel 25 and the base frame 22.
In addition, a circular hole 26 is formed on the base frame 22, slide guides 27 and 28 lifted from the base frame 22 and extended to the outside in parallel to the base frame 22 are formed around the circular hole 26, and lower rotating shafts 33b, 33b of a pair of link members 33, 33 are slidably supported by the slide guides 27 and 28.
In addition, split type bearings 30 and 31 for rotatably supporting upper rotating shafts 33a, 33a of the link members 33, 33 are formed on the back surface of the key top 23.
Pedestals 35 and 36 protrude from the base frame 22 outside the slide guides 27 and 28, respectively.
Before assembling the key top 23, when the lower rotating shafts 33b, 33b of the link members 33, 33 are inserted into the slide guides 27 and 28 in the level state, the upper rotating shafts 33a thereof are position-determined on the pedestals 35 and 36, respectively.
In addition, an elastic member 39 having a dome-shaped inside is mounted on the circular hole 26 of the base frame 22, and an upper end portion 39a of the elastic member 39 is position-determined on a position determining portion 23a of the key top 23.
In the assembly process of the conventional keyboard switch 21 as described above, the membrane switch 24 is inserted between the base frame 22 and the metal panel 25, and then the elastic member 39 is adhered to the circular hole 26 of the base frame 22 using an adhesive.
Then, the lower rotating shafts 33b, 33b of the link members 33, 33 are inserted into the slide guides 27 and 28 of the base frame 22, and the upper rotating shafts 33a, 33a thereof are positioned on the pedestals 35 and 36, so that the link members 33, 33 can be position-determined in parallel to the base frame 22.
When the upper rotating shafts 33a, 33a of the link members 33, 33 are position-determined on the pedestals 35 and 36 formed on the base frame 22, the position determining portion 23a of the key top 23 is positioned on the position determining portion 39a of the elastic member 39 in the upper portions of the link members 33, 33, and the key top 23 is pressed downward. Therefore, the upper rotating shafts 33a of the link members 33 position-determined on the pedestals 35 and 36 are inserted into the split type bearings 30 and 31.
And then, when pressure applied to the key top 23 is removed, the key top 23 is lifted to a predetermined position by an elastic force of the elastic member 39, and the lower rotating shafts 33b, 33b of the link members 33, 33 slide into the slide guides 27 and 28 to lift the upper rotating shafts 33a, 33a. 
[Patent Document 1]
Japanese Unexamined Patent Application Publication No. 11-16440
However, the conventional keyboard switch 21 requires the pedestals 35 and 36 that are members for determining the positions of the link members 33, 33 and thus uses the base frame 22, thereby increasing the number of components.
In addition, in an assembly process, the upper rotating shafts 33a, 33a of the link members 33, 33 must be position-determined on the pedestals 35 and 36 formed on the base frame 22, thereby increasing the number of assembly processes.